Per the Rome Foundation (McLean, Va.), the Rome II diagnostic criteria for functional bowel disorders (FBD) refer to various symptoms localized to the mid or lower gastrointestinal (GI) tract. FBD include numerous clinical subgroups, such as irritable bowel syndrome (IBS), functional diarrhea, functional constipation, functional abdominal bloating, etc. These disorders are characterized by a variable combination of chronic or recurrent GI symptoms that are not due to structural or biochemical abnormalities in the affected patients. IBS is the most common functional GI disorder, affecting a large number of adults worldwide. As the pathophysiology of IBS and other FBDs is not well understood and currently available drug regimens are very limited, there remains a need for methods and compositions suitable for relieving the symptoms of these disorders.